When a voltage differential is received across a pair of terminals in some components such as a capacitor having one or more sets of parallel plates, portions of the component can sometimes experience an attraction toward one another, which can result in a mechanical deformation in the component. In at least some instances, the deformation can be temporary, where when the voltage differential is removed, the component will substantially return to its undeformed state. In such an instance, when the voltage differential being applied is periodic in nature, a cycle of repeated deformations, which can include repeated contractions and expansions, can be produced.
In some of these instances, the repeated deformations, can produce a vibration having a frequency and amplitude, which will induce an auditory perceivable piezoelectric type effect. In at least some instances, the repeated deformation in the component can result in a vibration being induced in another nearby structure, such as a circuit substrate, which may be ultimately responsible for producing the auditory perceivable signal. In some such instances, multiple components being driven by a complementary signal may be arranged such that they together contribute in an additive manner to the nearby structure so as to result in the audibly detectable vibration.
Multiple components, such as capacitors, can be commonly associated with a complimentary signal, such as a power supply line to high current components. At least one example can include a radio frequency power amplifier in a cellular radio telephone type application. While in most instances, the capacitors are often sufficiently small so as to limit any corresponding vibration from producing a meaningful source of an auditory signal in the capacitor itself, when the capacitor exhibiting such an effect is mounted to a circuit substrate, such as a printed circuit board and/or the related metal shields, which generally will often have a much greater surface area, the capacitor can act as a point source mechanical exciter of the substrate. When grouped together with other point source mechanical exciters that add in a constructive manner at a frequency of concern, the multiple point source mechanical exciters can sometimes produce a perceivable effect in the circuit substrate.
Traditionally, the occurrence of such an affect between multiple commonly driven capacitors and an associated circuit substrate has been harder to manage and predict, because the way capacitors were previously manufactured and packaged resulted in a random orientation of the capacitors in the parts reels, and thus a more random arrangement of the various geometries of the capacitors relative to the surfaces of the circuit substrate upon which the components are received. As such, the effect might only randomly occur in a lot of produced boards. In such instances, past techniques for addressing any present audible noise in a particular board could include moving or removing one or more of the capacitors, adding a screw boss to the board to reduce movement, and selecting capacitors that did not exhibit the vibratory effect as strongly, such as tantalum capacitors. However, removing capacitors from a particular board can sometimes cause instability in the circuit. Adding additional screw bosses can affect circuit density and component placement including the placement of components relative to the circuit substrate, as well as the placement of components between the circuit substrate and the housing to which the substrate is being attached. Furthermore, the use of tantalum capacitors in some situations, such as on power lines, can be a safety hazard.
The present innovators have correspondingly recognized that recent changes, by capacitor manufacturers which allow capacitor orientation within a reel and correspondingly on a circuit substrate to be more predictable has allowed circuit board layout artists and designers to better anticipate and control the possible vibratory effects that placement of certain components can have upon a circuit substrate, and correspondingly the placement and orientation of components can be better managed to reduce the overall undesired vibratory effect that might be produced by the proximate placement of multiple components upon a circuit substrate.